Prepare the dressing: In a small bowl, whisk together the lime juice, olive oil, cumin, smoked paprika, minced garlic, and a pinch of salt. The mixture should look slightly cloudy and smell fragrant — the cumin and paprika will release their earthy aroma almost immediately.

Toast the corn (optional but recommended): Heat a dry frying pan over medium-high heat until a drop of water sizzles on contact. Add the drained sweetcorn and spread it into a single layer. Leave it undisturbed for 3-4 minutes — you'll hear a gentle popping sound and see the kernels turn golden brown and charred on one side. Stir once and cook for another 2 minutes until the colour is patchy and dark, then remove from heat.

Combine the beans and vegetables: In a large mixing bowl, add the rinsed black beans, toasted corn, diced red pepper, red onion, and spring onions. Toss gently with a wooden spoon — the colours should look vibrant against each other: deep black beans, bright yellow corn, crisp red pepper, and white onion.

Add the dressing: Pour the lime dressing over the bean mixture and stir well until everything is evenly coated. The beans will take on a glossy sheen, and the spices will cling to the vegetables.

Fold in the avocado and coriander: Gently add the diced avocado and chopped coriander. Stir very carefully with a rubber spatula so the avocado stays chunky — you want creamy pockets throughout, not a mashed paste. The avocado should still hold its shape and look bright green against the other ingredients.

Season and rest: Taste the salad — it should be tangy from the lime, warm from the cumin, and slightly sweet from the corn. Adjust salt and pepper as needed. Cover the bowl with cling film or a lid and let it rest at room temperature for at least 20 minutes. This resting time allows the beans to absorb the dressing, and you'll notice the flavours deepen and the texture become more cohesive.

Serve or store: Give the salad one final stir before serving. The avocado should still be intact, and the whole bowl should look fresh and inviting with flecks of green coriander throughout.